Molecular Electronics

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Molecular Electronics
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Molecular Electronics
See plastictransparencies,readingsfor details

• Tour wires
• Various molecular switches
• Various carbon nanotube devices
• Metal/semiconductor nano-wires
• Potential problem areas
• High resistance of some molecular devices.
• Maintaining thermal reliability in face of low
  node capacitances and voltages.
• High leakage currents, due to tunneling or
  thermal excitation over small, narrow barriers.

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Organic Molecules

• Schon/Meng/Bao, Bell Labs group
• Weiss_at_PSU, Reed_at_Yale
• Single-molecule switching, Science 22 Jun. 01

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Carbon Nanotubes

• Dekker group, Netherlands
• Nanotube transistor, 1998
• IBM research
• Nanotube NOT gates, June 2001

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Nano semiconducting wires

• Lieber group, Harvard
• Si/GaN semiconducting wires, few-nm diameter
• p-type n-type wires, logic gates

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Biochemical computing

• Selected points on DNA computing
• Adlemans experiment
• Cyclic Mixture Mutagenesis
• Reversible DNA Turing Machines
• Seemans self-assembling structures
• Winfrees tile self-assembly logics
• DNA computing has many disadvantages
• High cost of materials
• Slowness of diffusive molecular interactions
• Slowness/cost/unreliability of lab steps
• Prob. wont ever be a cost-effective computing
  paradigm (except maybe for in vivo apps)

Seereadingsfor details
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Optical computing

• Not viable at the nanoscale anytime soon!
• Due to entropy density issues mentioned earlier
• High enough info. flux requires extremely
  energetic photons, with too-high effective
  temperatures
• Or, waveguides considerably smaller than photon
  wavelengths - EMF theory suggests Impossible!
• All-optical computing requires nonlinear
  interactions, between photons materials.
• Optics (or more generally, EMF waves) will remain
  useful for communications, but only
• in contexts where extreme bandwidth density is
  not required (or extreme temperatures can be
  tolerated)